RESUMO
A new Leu-enkephalin peptidomimetic designed to explore the hydrogen bond acceptor ability of the third peptide bond has been prepared and studied. This new analog is produced by replacing the third amide of Leu-enkephalin with a fluoroalkene. An efficient and innovative synthesis of the corresponding dipeptide surrogate Fmoc-Gly-ψ[(Z)CFâCH]-Phe-OH is described. The key step involves the alkylation of a tin dienolate from the less hindered face of its chiral sulfonamide auxiliary derived from camphor. Once its synthesis was complete, its incorporation into the peptidomimetic sequence was achieved on a solid support with chlorotrityl resin following the Fmoc strategy. The peptidomimetic was characterized using competition binding with [125I]-deltorphin I on membrane extracts of HEK293 cells expressing the mouse delta opioid receptor (DOPr) and based on its abilities to inhibit the electrically induced contractions of the mouse vas deferens and to activate the ERK1/2 signaling pathway in DRGF11/DOPr-GFP cells. Together with our previous observations, our findings strongly suggest that the third amide bond of Leu-enkephalin primarily acts as a hydrogen bond acceptor in DOPr. Consequently, this amide bond can be successfully replaced by an ester, a thioamide, or a fluoroalkene without greatly impacting the binding or biological activity of the corresponding analogs. The lipophilicity (LogD7.4) of the active analog was also measured. It appears that fluoroalkenes are almost as efficient at increasing the lipophilicity as normal alkenes.
Assuntos
Ligação Competitiva/efeitos dos fármacos , Encefalina Leucina/química , Hidrocarbonetos Fluorados/síntese química , Hidrocarbonetos Fluorados/farmacologia , Peptidomiméticos/síntese química , Receptores Opioides delta/metabolismo , Animais , Linhagem Celular Transformada , Linhagem Celular Tumoral , Dipeptídeos/química , Encefalina Leucina/análogos & derivados , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Masculino , Camundongos , Peptidomiméticos/farmacologia , Fosforilação/efeitos dos fármacos , Ratos , Receptores Opioides delta/genética , Transfecção , Ducto Deferente/efeitos dos fármacos , Ducto Deferente/metabolismoRESUMO
Substitution of an ortho-fluoro or methoxy group in 1- and 2-naphthoic acids furnishing substituted naphthoic acids occurs in good to excellent yields upon reaction with alkyl/vinyl/aryl organolithium and Grignard reagents, in the absence of a metal catalyst without the need to protect the carboxyl (CO(2)H) group. This novel nucleophilic aromatic substitution is presumed to proceed via a precoordination of the organometallic with the substrate, followed by an addition/elimination.